Are safi weapons good/worth upgrading?

Hello everyone, I just got to the point where you do the safi raid and i got a few weapons from it (did it twice for now) but i have a few questions that remains without an anwser after some researchs

I use Switch Axe, and i got 2 Safi SA, the ice and sleep one. Are they worth using/upgrading? What skill should i try to get? I got something like : raging brach secret (agitator), affinity VI, and few other skills from the upgrades i did but i forgot and they prolly not good (i only upgraded the ice one for now)

Are they worth using? Been wanting to do a sleep build too so thats nice to get the SA for it

Regarding the general build, what armor should i go for?

Is it best to keep the safi material for his armor set when i unlock it or should i try to meld them for weapons since i want to get all the SA, or should i just do the raid

Thank you